1. Field of the Invention
The present invention relates to a method for manufacturing a header pipe which can be used as a tank in a heat exchanger.
2. Description of the Related Art
Conventionally, in a heat exchanger such as a capacitor or the like for use in a car, for example, as disclosed in Japanese Utility Model Publication No. Hei. 4-63982, a partition is provided in a header to thereby change the passage of fluid.
And, conventionally, a header with a partition of this type for use in a heat exchanger is manufactured in the following manner as shown in FIG. 15.
At first, a pipe member, which is formed of aluminum alloy and the outer surface of which is cladded with brazing material, is cut into a given dimension, thereby producing a pipe 11 for a header.
Then, in the pipe 11, there are formed tube insertion holes 13, a slit 15 for a divide, a fluid flow-in port 17, and a fluid flow-out port 19, respectively.
Next, an aluminum alloy divide 21 with the two surfaces thereof cladded with brazing material is inserted into the divide slit 15, and also two patches 23 formed of aluminum alloy are respectively pressure inserted into the two ends of the pipe 11 so as to manufacture a header pipe.
However, in such conventional header with a partition for use in a heat exchanger, use of an expensive pipe member which has been previously formed into a cylindrical shape increases the material cost thereof.
Also, the conventional header raises a fear that poor brazing can occur between the divide 21 and the pipe 11.
Conventionally, as a method which has solved the above problems, there is known a method for manufacturing a pipe with a partition disclosed in Japanese Patent Publication No. Hei. 7-314035.
According to the present method for manufacturing a pipe with a partition, as shown in FIGS. 16 and 17, there is manufactured a pipe with a partition structured such that it includes a partition portion 33 comprising a pair of semidivided partition portions 32.
In particular, this pipe with a partition is manufactured in the following manner:
At first, according to a molding step shown in FIGS. 18A-18C, a plate member formed of aluminum is molded so that there are formed a pair of semidivided cylindrical portions 35.
The pair of semidivided cylindrical portions 35 are arranged in parallel to each other with an arc-shaped connecting portion 37 between them.
And, in each of the pair of semidivided cylindrical portions 35, there is formed a U-shaped partition forming portion 39 which projects inwardly thereof.
Each of the pair of semidivided cylindrical portions 35 has a diameter smaller by 2 mm or so than the radius of a pipe portion 31 to be formed and, on the outside of each semidivided cylindrical portion 35, there is formed an edge portion 41.
The above-mentioned molding step can be achieved by holding the flat plate between given metal molds and then molding the same by pressing.
Next, according to a cutting step shown in FIGS. 19A and 19B, not only a portion of the connecting portion 37 situated between the partition forming portions 39 indicated by a shaded area A but also the edge portions 41 respectively situated on the two sides of the partition forming portions 39 are cut and removed together with the excessively increased thickness portions 41a of the edge portions 41.
This cutting step can be attained by trimming and piercing the flat plate using a piece of press work machinery.
Then, according to a compressing step, the partition forming portions 39 are respectively compressed from the two sides thereof in a direction of arrows B in FIGS. 20A and 20B to thereby form a semidivided partition portion 32.
This compressing step is tarried out in such a manner as shown in FIGS. 21A and 21B: that is, the outside portions of the two semidivided cylindrical portions 35 are held by a work holder 51 to be energized by springs 49, and, on the other hand, pressing members 53 are respectively disposed on the two sides of the partition forming portions 39 situated inside the two semidivided cylindrical portions 35; and, then, if the partition forming portions 39 are compression molded by the compressing members 53, then the semidivided partition portion 32 can be formed.
In the present compression molding operation, there is interposed a dimension correcting block 55 between the compressing members 53, so that the inward projecting length H of the semidivided partition portion 32 can be corrected by the dimension correcting block 55.
Next, according to an edge portion molding step shown in FIG. 22A and 22B, there are molded the two side edge portions 41 of the pair of semidivided cylindrical portions 35 in such a manner that, as shown in a lower side in FIG. 22, each edge portion 41 is formed in an arc shape which continues with its associated semidivided cylindrical portion 35.
This edge portion molding step can be achieved by holding the pair of semidivided cylindrical portions 35 between given metal molds and then molding the same by pressing.
Then, according to a mutually opposing step shown in FIGS. 23A and 23B, the connecting portion 37 is projected from the inside thereof to thereby dispose the pair of semidivided cylindrical portions 35 in such a manner that they are opposed to each other.
This mutually opposing step is carried out by storing the outside portions of the semidivided cylindrical portions 35 into a metal mold 57 and then pressing the connecting portion 37 against the arc-shaped portion 61 of the metal mold 57 using a punch 59.
Next, according to a butting step shown in FIGS. 24A and 24B, the mutually opposed semidivided cylindrical portions 35 are butted against each other.
This butting step is executed by storing the outside portions of the semidivided cylindrical portions 35 into a pair of metal molds (not shown) and then moving the metal molds. As a result of this, the semidivided cylindrical portions 35 are molded into a pipe shape.
Then, a connecting step is carried out: that is, not only the pair of semidivided cylindrical portions 35 but also the pair of semidivided partition portions 32 are connected to each other, so that the pipe with a partition shown in FIGS. 16 and 17 can be manufactured.
This connecting step can be achieved by performing, for example, a brazing operation using non-corrosive flux.
Now, FIGS. 25A and 25B show a header with a partition for a heat exchanger which is manufactured according to the above-mentioned method for manufacturing a pipe with a partition. The present header with a partition for a heat exchanger includes a partition portion 33 formed in the center portion of a cylindrically-shaped pipe portion 31A thereof.
Also, on one side of the outer periphery of the pipe portion 31A, there are formed a plurality of tube insertion holes 63 spaced at given intervals from each other.
Further, the openings of the two ends of the pipe portion 31A are respectively closed by cover members 65.
According to the present method for manufacturing a pipe with a partition, after completion of the edge portion molding step shown in FIGS. 22A and 22B, as shown in FIG. 26, there are formed, in one of the semidivided cylindrical portions 35, the tube insertion holes 63 in such a manner that they are spaced from each other at given intervals; and, at the same time, there are also formed a fluid flow-in port 67 into which a thermal medium is allowed to flow, and a fluid flow-out port 69 from which the thermal medium is allowed to flow.
This step can be achieved by slit/pierce molding using a piece of press work machinery.
In such header with a partition for a heat exchanger, since the pipe portion 31A including the partition portion 33 formed integrally therewith can be obtained easily, there is eliminated the need for use of the previously described expensive pipe member which has been previously formed into a cylindrical shape, thereby being able to reduce the material cost thereof greatly when compared with the previously described conventional header.
Also, when compared with the manufacture of the cylindrically-shaped pipe, the integral formation of the partition portion can reduce the number of parts, which makes it possible to reduce the cost of the header.
Further, since the tube insertion hole 63 can be worked in a semicircle state, the tube insertion hole 63 after molded can provide a sufficient strength, the working time thereof can be shortened, and thus the cost of the header can be reduced.
In addition, because the pair of semidivided cylindrical portions 35 and the pair of semidivided partition portions 32 can be connected to each other positively by brazing, it is possible to surely prevent the thermal medium from leaking externally from the partition portion 33.
However, according to the above-mentioned conventional method for manufacturing a pipe with a partition for use in a heat exchanger, in the molding step shown in FIGS. 18A-18C, as shown in FIG. 27, the radius R2 of the connecting portion 37 and the radius R1 of the semidivided cylindrical portion 35 are set substantially equal to each other, the peripheral length AB of the semidivided cylindrical portion 35, which extends from a connecting point A between the semidivided cylindrical portion 35 and connecting portion 37 to a virtual intersecting point B where a center connecting line L connecting the respective centers of the pair of semidivided cylindrical portions 35 with each other intersects the semidivided cylindrical portion 35, is set substantially the same as the peripheral length AC extending from the connecting point A to the center point C of the connecting portion 37; and also, the tube insertion holes 63 are respectively formed in such a manner that they extend up to the connecting portion 37. Hereupon, the end portion 63a of the tube insertion hole 63 is tapered to make the insertion of the tube into the tube insertion hole 63 easy in advance as shown in FIG. 28. However, if the mutually opposing step shown in FIGS. 23A and 23B and the butting step shown in FIG. 24 are carried out, then, there is raised a problem that the end portion 63a of the tube insertion hole 63 is deformed and the tapered portion is deformed so that the insertion of the tube into the tube insertion hole 63 becomes difficult.